The repair or replacement of in-service ocean telecommunications cable is extremely expensive, due in part to the cost of locating the cable in or on the ocean floor. Locating is made more difficult where the cable has been plowed into the ocean bed in areas of trawling, etc. In these situations, the cable-recovery vehicle must have a means to detect the buried cable's specific position before commencing the digging, acquisition and repair procedures.
Although location records usually exist by which the recovery vehicle can proceed to the approximate position of the buried cable, the final pinpointing is a very time-consuming and expensive operation heretofore involving much guesswork. One buried cable detection scheme of the prior art relies on a roving vehicle detecting the magnetic field generated when the cable is energized by a low frequency signal originating from the shore station. This method is restricted in its application, however, due to certain inherent limitations in signal application and recovery which make detection by this method uncertain and, in the case of certain cable systems, not possible.